The present invention relates to the production of construction materials and, more particularly to methods of and installations for producing mineral binders.
Widely known is a thermal method of producing mineral binders, in particular, Portland cement, wherein a particular mineral binder is produced by calcining or sintering an appropriate raw stock mixture in roaster furnaces followed by grinding the resulting sintered cake. The method, however, suffers from the following cardinal disadvantages: along sintering time as a rule, of at least several hours and the burning of much fuel to attain a sufficiently high temperature in the furnace, the maximum furnace temperature usually amounting to 1400.degree. to 1500.degree. C.
Another known method of producing mineral binders, Portland cement in particular, consists of exposing an appropriate raw stock mixture to an oinizing radiation, particularly, to an electron flux. As can be seen from published data, the method is carried out under high vacuum at absorbed radiation doses not in excess of a few hundredths of megarads per second (See, for example the method of producing Portland cement according to GDR Pat. No. 68451).
The latter method is advantageous over the thermal method in that it does not require any external heat supply and, therefore, saves fuel. At the same time, however, the radiation method suffers from the disadvantage that the binder formation process requires much time.
Also, the necessity of establishing a vacuum in the working chamber hampers industrial applications of the radiation method due to the commonly known fact that providing hermetically sealed working chambers is a complicated job under industrial conditions.
The known installations for producing mineral binders according to the aforesaid method are made as a hermetically sealed chamber having a charging device at its top and a discharging device at its bottom. Provided inside the chamber is an inclined chute for the starting stock to run therealong by gravity. Located above the chute is a source of ionizing radiation, most frequently an electron-flux source, emitting electrons substantially at right angles to the material to be irradiated (See, for example, the installation for producing Portland cement, clinker disclosed in GDR Patent No. 68451).
The main disadvantage of such installations lies, in our opinion, in that a vacuum must be established in the working chamber thereof, and also in the difficulties encountered when varying the rate of travel of the material under process along the chute within a sufficiently wide range depending on the power of absorbed radiation dose.
Also known in the art are installations for treating materials by exposure to an ionizing radiation, made as a hermetically sealed chamber accommodating a horizontal conveyer adapted to treasfer the material under process within the working chamber, and a source of a flux of accelerated electrons so arranged above the conveyer that the flux of electrons is directed at right angles to the conveyer carrying surface (See, for example, the installation disclosed in U.S. Pat. No. 2,887,584).
The main disadvantage of these installations resides in that they lack means for controlling the thickness of the material layer on the conveyer.